Mining cutter bit block



2 Sheets-Sheet 1 Filed March 12, l955 N T. E R ma 1 w 2 M M 7 "ND; a

an warm/ x k a, 2 5g 2 /-7 T'T'URNEV United States Patent MINING CUTTER BIT BLOCK Clarence H. Brown, Chicago, lll., assignor to Goodman Manufacturing Company, Chicago, 111., a corporation of linois Application March 12, 1953, Serial No. 341,976

3 Claims. (Cl. 262-33.)

This invention relates to improvements in kerf-cutting bit blocks of the kind particularly adapted for use in coalcutting and has for its principal object to provide an improved form of cutter bit and block permitting ready adjustment of the working length of the bit to compensate for wear on the end of the cutter bit during use.

Other objects and advantages of the invention willappear from time to time as the following description proceeds.

The invention may best be understood by reference to the accompanying drawings, in which:

Figure l is a side view of a cutter chain block and bit constructed in accordance with my invention;

Figure 2 is a longitudinal section of the block and bit shown in Figure 1;

Figure 3 is a perspective view of the block and bit, with one side wall of the block broken away;

Figure 4 is a section taken on line 44 of Figure 1;

Figure 5 is a fragmentary section similar to Figure 2, but showing a modified form of bit and adjusting screw.

Referring now to details of the embodiment of my invention shown in Figures 1 to 4, indicates generally a cutter bit block of more or less conventional form used in endless kerf-cutting chains, including a body 11 with bosses 12, 12 projecting in opposite directions from its base to provide pivotal connection with connecting links of conventional form (not shown). The body 11 is provided with a bit-receiving upright aperture 13 open to the top face of the block body. As will be understood by those familiar with the art, individual cutter chains usually have bit-receiving apertures arranged at several different angles with respect to the plane of orbital movement of the cutter chain so that the bits project at similar angles to cut a kerf substantially wider than the blocks and connecting links which make up the cutter chain. In the illustrative form shown, the bit 15 and its aperture are disposed in what is commonly termed the center position but it will be understood that the bit and bit-receiving aperture can be inclined at varying angles toward one side or the other of the block, as desired.

The cutter bit 15 has a generally straight shank 16 with a cutting portion indicated generally at 17 at its outer end. This cutting portion may be of different shapes, in the form shown the cutting portion including a wedge-shaped tip 18 made of tungsten carbide or similar wear-resisting material such as commonly employed with cutter bits.

Referring now more particularly to the novel features of my invention, the shank 16 of the bit is provided with a series of transverse serrations 19, 19 along its rear edge opposite to the front edge which carries the cutting tip 18. The rear face of the shank has conventional flat bearing faces 19a, 19b above and below the serrations 19.

A threaded bore 20 is formed in the rear face of the cutter block in a generally horizontal relation thereto and communicating with the bit-receiving aperture 13. An adjusting set screw 21 is threaded in the bore 20, this set screw having a diametrically widened wedge-shaped end 22 adapted to have fitting engagement in one of the serrations 19 along the rear edge of the bit shank 16. Said adjusting screw is provided with a head 23 adapted to project beyond the rear face of the block, for engagement by a wrench.

A second threaded bore 24 extends through the front face of the block for reception of a locking set screw 25, which may be of conventional form commonly employed for locking cutter bits in place in cutter blocks.

is adapted to bite a ring-shaped impression on the front edge of the bit shank when tightened thereagainst.

In the preferred form shown herein, the two threaded bores 20 and 24 for the adjusting and locking screws, respectively, are, for convenience, made as a continuous through-bore of the same size and on a common axis. It will be understood, however, that the adjusting screw 21 and its bore can be made of a different size and disposed on a somewhat different axis than that of the locking set screw 25, if desired.

It will be understood that, with many conventional forms of cutter blocks and bits, the conventional locking screw 25 is the sole means of holding the bit in place, so that such locking screw is also relied upon for holding the bit at the proper cutting length beyond the upper face of the block. Accordingly, if such locking screw should work loose even slightly, the bit will tend to slide backward out of engagement with the coal, or may even be loosened sufficiently to fly out of the cutter block by centrifugal force as it passes around the end of the cutter bar on which the chain is mounted.

With my improved form of bit mounting including the adjusting screw 21 in addition to the conventional locking screw 25, it will be understood that the locking screw is relied upon, as before, to press the plane surfaces 19a, 19b of the bit shank firmly against the rear surface of the bit-receiving aperture 13, and that the primary purpose of the wedge 22 on the adjusting screw 21 is to be engaged in one of the serrations 19 to a depth sufficient to maintain the cutter bit at approximately the desired cutting height, to compensate for the amount of wear that has been imposed upon the cutting tip 18. Accordingly, in practice, the adjusting screw 21, including the wedge 22, is initially screwed into a position where the Wedge portion 22 projects into the bit-receiving aperture 13 a distance approaching, but preferably not exceeding, the depth of the serrations 19, 19. The shank of the bit is then inserted in the bit-receiving aperture 13 which, as shown, is substantially wider longitudinally of the block than the shank. The bit shank is then moved rearwardly so that the wedge 22 will engage the proper serration on the shank to hold the bit at the desired cutting height. Thereafter, the locking screw 25 is screwed home against the front face of the bit shank to secure the latter firmly in place with the rear surfaces 19a, 19b of the bit shank in engagement with the front face of the bit-receiving aperture.

From the above description, it will be understood that the Wedge-shaped adjusting screw 21 is not intended to force the shank of the cutter bit away from the rear face of the receiving aperture 13 in opposition to the conventional locking screw 25, but it is preferably employed solely as a means for initially setting, and then retaining, the shank against endwise movement at a predetermined cutting length.

Figure 5 shows a modified form of device, in which the end 30 of the gauge-setting screw 21a is substantially rectangular in cross section and has fitting engagement in a series of correspondingly shaped serrations 31, 31 in the rear face of the bit shank 16a. In other respects, the device is adapted to provide the same type of adjustment of the bit length as is provided with the wedge- Such. locking screws usually have a cup-shaped end 26 which shaped form of serrations and gauge screw shown in Figures 1 to 4.

Although I have shown and described certain embodiments of my invention, it will be understood that I do not wish to be limited to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In a cutter bit block, a cutter bit having an elongated shank, a block having an elongated aperture having parallel front and rear inner walls for slidably receiving the shank of said cutter bit, a locking screw threaded in one face of said block and projecting into said bit-receiving aperture for engagement with one side of said cutter bit shank substantially at right angles thereto, the opposite side of said shank having aligned plane bearing surfaces intermediate its ends with a plurality of serrations therebetween, an adjusting screw threaded in said block for selective engagement with said serrations, said opposed sides of said shank being substantially parallel and spaced apart a lesser distance than the front and rear inner walls of said bit-receiving aperture, said bit shank being adapted for endwise adjustment in said bit-receiving aper- 4 ture by selectively engaging one of the serrations in one face by the end of said adjusting screw, and then locking said bit shank in such adjusted position by said locking screw to force the two aligned plane surfaces of said bit adjacent said serrations against the proximate inner face of the bit-receiving aperture.

2. A cutter bit block in accordance with claim 1, wherein the two set screws are of the same pitch diameter and are adapted to be disposed in opposed longitudinal alignment with each other in the front and rear of the bit block.

3. A cutter bit block in accordance with claim 2, wherein the adjusting screw has a diametrically widened end having selective fitting engagement within the serrations in the bit shank.

References Cited in the file of this patent UNITED STATES PATENTS 

